1. Field of the Invention
The present invention relates to a blood pressure measuring apparatus and a method of measuring blood pressure, and more particularly, to a blood pressure measuring apparatus used for a tonometry test method and a method of measuring blood pressure.
2. Description of the Related Art
Blood pressure is classified into arterial blood pressure, capillary blood pressure, and vein blood pressure. Generally, blood pressure indicates the arterial blood pressure that varies according to heartbeat.
In a tonometry test method, which is one of the methods of non-invasively measuring blood pressure, blood pressure is measured by pressing a pressure sensor in a direction of a radial artery after locating the pressure sensor on the radial artery of the wrist. At this point, a sensing unit of the pressure sensor deforms due to blood pressure, and thus, the blood pressure is measured by measuring the deformation of the sensing unit.
The pressure sensor for measuring blood pressure outputs a pressure value as an electrical signal, and the electrical signal is processed so as to be read as blood pressure. The pressure sensor and a signal processing system constitute a blood pressure measuring system.
When blood pressure is measured from the radial artery of the wrist, which is a measuring point, and one pressure sensor is used, the pressure sensor must be correctly located on the radial artery to accurately measure blood pressure. For this purpose, the maximum blood pressure is measured by moving the pressure sensor using an actuator. However, in this case, since the actuator is necessary, the realization of a compact blood pressure measuring apparatus is difficult.
Instead of using the actuator, a plurality of pressure sensors may be used. In this case, a sensor signal detected from a position where a biomedical signal is the largest among several sensor signals may be used. This method is advantageous for realizing a small and lightweight blood pressure measuring apparatus since an actuator is unnecessary. Theoretically, if small pressure sensors are disposed in a row, at least one pressure sensor is located on a correct location of the radial artery.
However, if the number of sensors is low due to an area of the pressure sensor, the sensitivity of finding the position of radial artery of the wrist is reduced, and thus, an accurate measurement of the blood pressure is difficult.
Also, if the number of sensors is increased by reducing sensor areas, it will take time to find the position of the radial artery of the wrist by calculating the amplitude of a pulse wave of each of the sensors.